What do the following two equations represent? $4x+4y = -3$ $-4x+4y = 1$
Explanation: Putting the first equation in $y = mx + b$ form gives: $4x+4y = -3$ $4y = -4x-3$ $y = -1x - \dfrac{3}{4}$ Putting the second equation in $y = mx + b$ form gives: $-4x+4y = 1$ $4y = 4x+1$ $y = 1x + \dfrac{1}{4}$ The slopes are negative inverses of each other, so the lines are perpendicular.